Electric heater



fi 631,484 June 1927' w. E. HUDSON ELECTRIC HEATER Filed March 50. 1925 2 Sheets-Sheet l 3Q INVENTOR m 5 HM Wm ATTORNEY June 7 1927.

w. E. HUDSON ELECTRIC HEATER Filed March so. 1925' 2 Sheets-Sheet, 2

INVENTOR ATTORNEY Patented June 7, 1927.

UNITED STATES PATENT OFFICE.

WALTER E. HUDSON, OF AMAGANSETT, NEW YORK, ASSIGNOR TO HUDSON HEATING SYSTEMS, INC., OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

ELECTRIC HEATER.

, Application filed March 30, 1925.

This invention relates generally to electric heaters and is more particularly designed to for manual or automatic" control of said circuits, and controlling devices sensitive to temperature for automatically operating said switcheswhereby the consumption of current fora given installation may-be reduced and the life of the resistors prolonged. This application is in part a continuation of my pending application, Serial No. 672,367, filed November 2, 1923. a

The underlying principle of the invention involves the employment of a plurality of resistor-sin each heating unit which may be connected up all in series, or all in multiple, or partly in series and partly in multiple according to the amount of heat to be gen erated,fand, in its preferred form, also involves the employment of thermostatic devices variously disposed for automatically producing the results.

variations in circuit connec tions necessary to secure the above lndicated The invention is particularly adapted for the heating of buildings, railway cars, and other spaces in which a substantially uniform temperature is to be maintained what ever the temperature of the external atmosphere.

The best form of apparatus at present known to me is illustrated in the accompany- F ig. 1 is a trical circuits ing two sheets of drawings in which,

general dlagram of the elecwith means controlled by thermostats for connecting together the coils of different electrical units in various relations to produce different amounts of heat from a current supply circuit o'f constant voltage.

Fig. 2 is a side view of the cylindrical switch used for this purpose, with its casing shown in section. r I

Fig.3 is a cross section of said switch cylinder, on line 3-3 of Fig. 2, and

f Fig. 4 is a'view of the other end of the switch, showin this cylinder.

g the mechanism for rotating Serial No. 19,202.

Throughout the drawings like reference characters indicate like parts.

One object to be attained in any electric heating device is the prolonging of the life of the heatin coils by subjecting them to the action of on y a moderate amount of cur- .rent when only a moderate degree of heat is required from them.

Another equally important object is reduction of the first cost-of the heater by keeping the wire in it down to the minimum length and cross section which will.still give the needed heat in midwinter, when carrying the maximum amount of current permissible without destructive action on the heater coils. Of course the current supplied is at a constant voltage and, if the coils of the .heating element are connected up permanently in any one particular manner, the two sets of conditions tending to produce the two above desired results, are conflicting. According to my invention, however, both the above objects can be attained in one in stallation by dividing the heating wire thereof into a number of separate coils, each one of which will have a resistance just sufficient to raise it to the highest permissible temperature when current of this constant voltage is supplied to it, so that the maximum heat output may be' obtained by connecting all these coils in multiple with the supply circuit, (as in mid-winter), and then providing means for connecting all or certain of these coils together in series groups, each of much greater total resistance than a single coil, when a less amount of heat is to be generated (as in fall or spring, or during mild winter days). When this is done one or another of the series connections can be used during eighty or ninety percent of the time the heater is in use, with the result that the wires are then heated only to moderate temperatures which they can endure for a long time, and yetywhen a cold snap comes on for a few days the heater has the capacity, when its coils are all thrown into multiple connection, of maintaining the predetermined room temperature even if the exterior temperature drops to the lowest recorded de gree for that locality. 10o

Referring to the particular embodiment of the invention shown diagrammatically In Fig. 1, S is a dynamo or other source of electric current supply, A, A, one wire of Iseparate current supply sub-circuit which several sub-circuits may be connected together or each connected directly to the main circuit A, B, or both. The three coils or groups of coils 59. 59 and .59 form the members of a heating unit or set, which unit may be placed in operative. position in a water heater or steam boiler (as shown in my above noted pending application) or may be located in contact with the air in a room or car or other compartment which is to be heated directly. In any ordinary practical installation there would be a number of such heating units or sets in multiple with the main supply circuit A, B.

' The coils of each member of all the sets may be bridged across the supply circuit in multipi or parallel from A. to B, or the coil members 59 and 59" of each set may be connected in series across the supply circuit, while members 59 of each set are connected in multiple, or parallel across said circuit, or all three members 59, 59 and 59", of each set may be connected in series, all these sets, of course, being in multiple across the supply circuit.

In the first above suggested arrangementall the members of all the sets of coils would carry the predetermined max mum current and deliver the maximum amounts of heat of which they were capable without rap d disintegration occurring asa result. In the second suggested arrangement the series coupled coil-pairs, 59 and 59 of each set would be heated only to a moderate degree, as the doubling of the total resistance resulting from connecting them in series would cut the current flowing through them to one half of the maximum permissible quantity, and the heat generated thereby to one quarter, but coil members 59 of each set would still be maintained at maximum temperature because they would be carrying full current. In the third above suggested arrangement, all of the coil members of all the sets would be but slightly heated because the total resistance caused by connecting all three members of each set in series would be three times that of one member, and this would reduce the current carried by each to one third of the maximum, and the heat generated thereby to one ninth of the amount created when the multiple connection is employed.

The problem then is to devise a circuit changing apparatus capable of producing these shifting arrangements of the connections from multiple to series-multiple and to series, and to operatethis automatically by thermostatic means.

The basic method of regulation adopted is the usualone of opening and closin' the supply circuit automatically by an a justable thermostat placed in the house being heated. If this is set at degrees F ahrenheit it opens the supply circuit when 70 degrees Fahrenheit is reached and closes it again when the temperature drops a predetermined number of degrees, say to 65 Fahrenheit.

The arrangement of the coil members of each set or unit either into series-multiple or into series relation is effected by a thermostat controlled by the circulating water or by an aquastat immersed in said heated water if a'hot water heating system is used. When the water rises to 180degrees F ahrenheit, or other predetermined point, the

aquastat therein switches the coils into series, I

so that little more heat will be given to the water'even while the supply circuit is closed; and, of course, Whenever the room temperature rises to 70- the room thermostat will open the supply circuit and stop all heat generation. If an indirect air heating system were used this thermostat would be placed in the current of heated air. If the electric heaters are placed in the room to be heated this thermostat might be placed on the casing of such heater. I

The arranging of all coil members of all sets n multiple or parallel across the supply circuit is effected by an outdoor thermostat so connected up with the switching system that when the atmospheric temperature drops to a given point, say 10 degrees Fahrenheit, this multiple arrangement will be produced and maintained as long as the outdoor temperature remains at or below 10 degrees. When that thermostat is subjected to a temperature above 10 degrees it reinstates the series-multiple arrangement. While the multiple arrangement is in existence, the second, or water controlled circuit, is disabled, so that there is no possibility of this arrangement of multiple connec: tion being modified by any variation in water temperature. Regulation of room temperature is solely controlled by the open- 1ng or closing of the supply circuit by operation of the room thermostat first above referred to.

The foregoing operation and shifting of circuits to produce the described results in the manner outlined may be efiected in a variety of ways, but the simplest apparatus now known to me is that shown herein in which: 21 is the motor for a motor-operated snap-switch 22, the circuit for which motor is controlled by thermostat 23 located in the house or apartment to be heated. 24,24, are contacts which when bridged by switch 22 as indicated in full lines in Fig. 1, will close circuit 25, so that-current will flow from A through solenoid 26, contacts'24 and Wires 25*, and to B. The consequent pull of solenoid 26 on its core will close circuit breaker27, overcoming the tension of spring 27*. This will connect the supply circuit with the heater coils 59, 59", and 59, however they ma be connected together, and these coils wil begin to heat the water in the hot water circulating system, if such system is employed, and the heated water will rise to the radiators in the rooms and begin to raise the temperature of the air therein. When this air is heated to 70 degrees the tongue of thermostat 23 will touch contact 30, current will'flow from A through wire A motor 21, thermostat 23, contact 3( switch 22 bridging contacts 24, 24, wires 25, 35 and 45 to B. This will operate motor 21 and snap switch 22 intodotted line position bridging contacts 28, 28, which opens circuit 25,'deenergizes'solenoid 26 and allows'spring 27 to open circuit breaker 27,

thus cutting off current from. the heater.

en thereafter thehouse interior cools down to 65 degrees thermostat 23 closes on contact 29, current passes from A through A motor 21, thermostat 23, contact 29, switch contacts 28, 28, wires 25, etc. to B. This rotates snap switch 22 around to contacts 24, 24, again and cuts oiit the motor, leaving the switch in this position with the circuit closed through solenoid 26, whlch closes circuit breaker 27 and throws the heaters into operation again as originally described. This alternate opening and closing of the supply circuit to the heaters by operation of thermostat 23 controlled by room temperature :goes on in all kinds of weather and whatever the internal arrangement of the heater circuits may be.

The next things in logical order of description of a hot water heating-system are the internal heater circuits and the thermostat-controlled means for shifting their arrangement from multiple to series-multiple supply ci-rci'iit,-and with brushes 58, on the and series, as may best suit conditions.

These circuits are controlled by a rotatable maisterswitch compo ed of a cylinder-'51 of non-conducting material (Figs. 2, 3and 4) which is mounted on shaft 52 in casing 53, and which carries certain contacts 56, 60, 61 and-62 cooperating with brushes or contact springs 57, 57, forming the terminals of the terminals of the heater coils. Contacts '56, are ring-shaped and simply rotate under the brushes 57 and under the end members of the series of brushes-58. Contacts 60 are connected to rings 56, or to one another, as shown in Fig. 1, so that when cylinder 51 is in the mid-position shown in Fig. 2 and four of the brushes 58 rest on these contacts 60, the heater coils 59 and coils are in series-multiple connection.

59" of each set will be connected in series one with the other across the supply circuit, while coil 59 of each set will be connected across the supply circuit separately. If cylinder 51 is thereafter-rotated in a counterclockwise direction (looking at Fig. 4) so that contacts 61 which are connected together in pairs as shown in Fig. 1, come under brushes 58, all the coils 59, 59" and 59, of

each setwill be connected together in series.

If, on the other hand, cylinder 51is rotated in a clock-wise direction so that brushes 58 rest on contacts 62, which are connected in pairs to'rings 56, all three coils will be connected in multiple or parallel across the sup-' ply circuit.

The thermostatic control apparatus for etfecting these partial rotations of the cylinder switch comprises a collar 63 fast on the end of shaft 52 and provided with an upwardly projecting arm to which the centering springs 54, 54 are connected, a notch on its under face with which spring pressed centering pin 55 engages, and laterally extending arms to which the cores of solenoids 36 and 46 are connected '(all'as shown in Fig. 4) together with thermostatically con trolled circuits for energizing and deenergizing these solenoids.

When the switch cylinder 51 is in midposition, as shown in Figs. 3 and 4, both wise direction to bring contacts 62 under ti le. The circuits controlled by the temperature of the circulating water include aquastat 33, immersed therein, snap switch 32 and motor'31kf0r operating said switch. When the water temperature is below 180 but above 170 aquastat 33 is in mid-position. Solenoid 36 is not energized andsprings 53 hold the parts in position shown in Figs. 2, 3 and 4. The heater coils are therefore in series-multiple connection and the water temperature will gradually rise. When it reaches 180 aquastat 33 touches contact 39 and closes a circuit from A, through A A motor 31, aquastat 33, contact 39, switch 32 shown in dotted line position bridging contacts 38, 38, wires 35 and 45 to B. This operates brushes 58 and put the heatercoils in mulmotor 31-to snap switch 32 over into full line out the motor and also completes a circuit from A through wire 47 (if circuit breaker 27 is closed), solenoid 36, circuit breaker 37 (if closed), wire 35, switch 32 brid%ng contacts 34, 34, wires and 45 to This energizes solenoid 36. torotate switch cylinder 51 in a counter-clockwise direction to bring contacts 61 under brushes 58 and thus puts the heater coils in series. The small amount of heat thereafter delivered from these series coils to the water may keep it between 180 and 170 for a long time, thus saving current, but whenever the water temperature falls to 170, a uastat 33 swings onto contact and establi shiesa" circuit from A through A,, A,, motor 31, aquastat 33, contact 40, switch 32 bridging contacts 34, 34, wires 35 and to B. This rotates motor 31 and snaps switch 32 over onto contacts 38, 38, cutting out the motor and breaking the circuit t rough solenoid 36. Centering springs 54, 54 then pull cylinder switch 51 back into mid-position with contacts under brushes 58, the heater coils go back into series-multiple connection and thenecessary' additional heat is then supplied by them to the circulating water to eep it above 170. Whenever the water temperature reaches 180 again the coils are put back in series as first above described.

The control by the out-door temperature is effected through thermostat 43 which is exposed to the outer atmosphere. So long as the outdoor temperature is above 10 de-.'

grees or any other predetermined temperature, thermostat 43 is either in mid-position or closed on contact 50, but as switch 42 is then in dotted line position bridging contacts 48, 48, (having been left there by a previous operation) the circuit through motor 41 and solenoid 46 is open at 44, 44, and cylinder switch 51 is left free to be controlled by solenoid 36 in the manner previously described. If the outdoor temperature falls below 10 degrees, however, thermostat 43 closes on contact 49. A circuit is then established from A, through A,, A A,, motor 41, thermostat 43, contact 49, switch 42 in dotted line position bridging contacts 48, 48, and wire 45' to B. ThIS rotates the motor and snaps switch 42 into full line posi tion onto contacts 44, 44. This cuts out the motor but establishes a circuit from A throu h wire 47 (if circuit breaker 27 is closed% through solenoid 46, wire 45, switch 42 bridging contacts 44, 44, and wire 45 to B. Solenoid 46 being thus energized rotates cylinder switch \51 in a clockwlse direction putting contacts 62'under their cooperating brushes 58 and throwing the heater coils 59, 59 and 59 into multiple, or parallel arrangement across the supply circuit. This puts the heater in conditlon to consume the maximum current and deliver its maximum output. Whenever the outdoor temperature rises a predetermined amo'unt above 10 de- A,, A A,, motor 41, thermostat 43, contact 50, switch 42 in full line position brid 'ng contacts 44, 44, and wire 45 to B. is

rotates the motor, snap ing switch 42 on- To prevent a temperature of the circulation water above 180 degrees energizing solenoid 36, as before described, and thus neutralizlng the action of solenoid 46, in cold weather,

I disable the circuit for 36'by having sole-v noid 46, whenever energized, also ull open circuit breaker 37. perature is above 10 and solenoid 46 deenergized, spring 37 closes this circuit breaker and reestablishes the possible circuit through solenoid 36, for the normal operation in mild weather before explained. I

It should be remembered that no matter whether the coils are in multiple under control of thermostat 43, or in series-or seriesmultiple under control of aquastat 33, the lndoor thermostat 23 is operating continuously, under variations of room temperature, to close or open the current supply circuit according as the room gets too cold or too hot, with the particular amount of current then being consumed by the heater coils 59 59" and 59.

Yarious'changes can be made in the details of construction above described without-departing from the underlying principles of the invention so long as the general methods of construction and operation thereby lllustrated, are retained. Certain features of my invention could also be omitted in particular cases without seriously reducing its efliciency and usefulness of the remaining portions of the combination. Other forms of electro-magnetic motor devices could be substituted for the solenoids and movable cores therefor herein shown.

As previously explained, the invention has been described in detail as applied in a system in which water is the heat conveying medium or heat transferring agency as being perhaps, the best practical embodiment thereof. If, however, the heat of'coils 59", 59 and 59 'were transferred to a current of steam or air which was conducted from such heating source to the roomor rooms to be heated thereby, the thermostat 33 could then be placed in the steam passage or on the lVhen the outoor temboiler, or in the current of air, as occasionmight require .or render most advisable. Also if said electric heating coils were placed in the room 'or car to be heated for directly heating the same, the casing or support for said coils, and the metal of the coils themselves, would form the heat transferring agent or medium by which the atmosphere of said room or compartment was heated, and thermostat 33 would then be placed in the heater casing, or directly on the heater or on its support, so that it would be similarly responsive to the local temperature at or in the coils and thereby regulate the circuit connections therefor 1n the manner above described;

Having describedmy invention I claim:

1. In an electrical system for heating buildings and the like the combination of a suitable heat conveying medium, an electrical heating unit in operative relation with said medium and adapted to transferheat thereto, which said unit comprises a plurality of separate current resistors, a current supply circuit of substantially constant voltage, means responsive to variations in temperature of said medium for connecting said resistors in parallel or in series with said supplycircuit and independent means for controlling current in said supply circuit responsive to variations in temperature of the atmosphere of the space being heated.

2. In an electrical system for heating buildings and the like the combination of a suitable heat'conv eying medium, an electric heating unit in operative relation with said medium and adapted to transfer heat there= to, which said unit comprises a plurality.

v interiors of buildings and the like the combination of an electrical heating unit comprising a plurality of "separate current resistors, a current suppl circuit therefor, a thermostatinside the uilding adapted to open and close said supply circuit, and

means for varying the connections of saidv resistors to said supply circuit and to. one another which said means comprises a thermostat responsive to the temperature ofthe atmosphere exterior of the building.

4.. In an electrical system for heating the interiors of buildings and the like the combination of an electrical heating unit com prising a plurality of separate current resistors, a current supply circuit therefor, and means for varying the connections of. said resistors to said supply circuit and to one another, which said means comprises a thermostat responsive to the temperature of the atmosphere exterior to the building.

5. Inan electrical system for heating the interiors of buildings and the like the-flcom- 'a predetermined point.

bination of an electrical heating unit comprising a plurality of separate current re-f sistors, a current supply circuit therefor, and means for varying the connections of said resistors to said supply circuit and to one another, which said means comprises a thermostat responsive to the temperature of the atmosphere exterior to the building and means responsive to variations of temperature of the space being heated.

6. In an electricalsystem for heating the interiors of buildings and the like the combination ofan electrical heating unit comprising a plurality of separate current resistors, a current supply circuit therefor, and means for varying the connections of said resistors to said supply circuit and to one another, which said means comprises a thermostat responsive to the temperature of the atmosphere exterior to the building and adapted to throw said resistors into parallel connection with said supply circuit whenever said exterior temperature falls below 7 In an electrical system for heating buildings and the like the combination of a suitable heat conveyingmediur'n, an electrical heating unit in operative relation with said medium and adapted to transfer heat thereto, which said uni-t comprises a plurality, of separate current resistorsfa current vsupply circuit of substantially constant voltage,means responsive to variations in the temperature of said medium adapted to shift the said resistors from series connection with said su 1y circuit to a different arrangement an back again to series, and means responsive to decreases in temperature of the atmosphere exterior of the building for shifting all saidresistors into multiple con- 5 nection with said supply circuit.

8. In an electrical system for heating buildings and the like the combination of a suitable heat conveying medium,'an electrical heating unit in operative "relation with said medium and adapted to transfer heatthereto, which said unit comprises a plurality of separate current resistors, a current supply circuit of substantially constant voltage, means responsive to variations in the tem- 116 perature of said medium adapted to shift the said resistors from series connection with said supply circuit to a different arrangement and back again to series, and means responsiv'e to decreases in temperature of the 120 atmosphere exterior of the building for shifting all said resistors into multiple con nection with said supply circuit together with a thermostat responsive to changes in temperature of the atmosphere of the space being heated and adapted to open and close said supply circuit. v

9. In an' electrical system for heating buildings and the like the'combination of a suitable heat conveying medium, an electrical 1.50

heating unit in operative relation with said medium and adaptedto transfer heat thereto, which said unit comprises a plurality of separate current resistors, a current supply circuit of substantially constant voltage, means responsive to variations in the temperature of said medium adapted to slnft the said resistors from series connection with said supply circuit to a different arrangement and back again to series, and means responsive to decreases in temperature of the atmosphere exterior of the building for shifting all said resistors into multiple connection with said supply circuit, and for contemporaneously disabling said first mentioned means.

10. In an electric heating system the combination of an electrical heating unit comprising a plurality of separate current resistors and means for connecting sa1d resistors all in series, or all in parallel, or

some in series one with another, and another resistor inparallel with said last mentioned series.

11. In an electric heating system the combination of an electrical heating unit comprising a plurality of separate current resistors and means for connectin said resistors all in series, or all in paralleI, or some in series with another, and another resistor in parallel with said last mentioned series together with a plurality of separate automatic devices each'adapted to produce some of the above specified variations in resistor connections, and each responsive to the local temperature to whichit is exposed.

12. In an electric heating system the combination of an electrical heating unit comprising a plurality of separate current resistors and means for connecting said res1stors all in series, or all in parallel, or some in series one with another, and another resistor in parallel with said last mentioned series together with a plurality of separate automatic devices each adapted to produce some of the above specified variations in resistor connections, and each responsive to the local temperature to which it is exposed, one

of said automatic devices being located in the interior of a building in which said unit is placed and another being exposed to the atmosphere exterior of said uilding.

13. In an electrical system for heating buildings and the like the combination of a suitable heat conveying medium, an electrical heater comprising three separate cur.

' circuit, means for connecting said resistors in series with said supply circuit, or in parallel therewith, or two of them in series therewith and the other directly across said supply circuit, a thermostat located in the space to be heated adapted to control the current in said supply circuit, a device responsive to variations in temperature of said heat conveying medium adapted. to shift said resistors from series to the above mentioned series and multiple connection with said sup ply circuit and back again, and a thermostat exposed to the atmosphere exterior of the building adapted to shift said resistors from theabovc mentioned series and multiple connection to multiple connection with said supply circuit and back again.

14. A combination such as set out in claim 18 in which the last mentioned thermostat is also adapted while the multiple connection is established to disable the device which is responsive to variations of temperature in said heat conveying medium.

15. In an electric heating system the combination of heating and current supply elec tric circuits, as master switch controllingthe connection of said heating circuits to said supply circuit which said switch comprises a foundation of insulating material, two

parallel conducting strips mounted thereon, on which strips the terminals of the supply circuit may bear, a set of contacts mounted. on said foundation on which the terminals of all the heating circuits may bear and be thereby connected in series with the supply circuit, a second-set of contacts by which said heating circuits may be similarly connected in multiple and a third set of contacts by which said heating circuits may 7 be similarly connected partly in series and partly in multiple, and means for moving said switch foundation along the line of said parallel strips, whereby the respective sets of contacts'above described may be successively brou ht under the heating circuit terminals whi e said parallel strips are con temporaneously under said supply circuit terminals and the relative connections 013 said heating circuits be thereby shifted accordingly.

16. A circuit controlling device for an electric heating system, which'device comprises, incombination a cylinder of insulating material, means for rotating said cylinder, two

rings of conducting material mounted and spaced apart thereon, three rows of four separate contacts each mounted on said cylinder surface and extending between said rings, two supply circuit terminals resting one on each ring, and three airs of work circuit terminals arranged with the outermost member of each outside pair resting O e f said rings, and the remainder rent reslstors H1 operative relation to said heat conveying vmedium, a current supply adapted to bear each upon one of said contacts when said cylinder is rotated to the proper extent, the contacts of one row being connected together in two pairs, two of the middle row being connected together and the others connected one to one ring and the other to the other ring, and one member of each pair of the third row being connected to one ring while the other member of each is connected to the other ring, whereby on rotation of said cylinder said work circuits are connected in series with said supply circuit, in parallel therewith, or two in series therewith and the third bridged directly across said supply circuit according to the extent of rotation of said cylinder. 7

17 A combination such as set out in claim said contacts.

- WALTER E. HUDSON. 

